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74LS154 non-inverted equivalent?

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neazoi

neazoi

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The 74LS154 is a common 4 to 16 demultiplexer and its outputs are inverted. Is there any equivalent that it's outputs are non-inverted?

What If I need more pins, is there any easy to find 6 to 64 demultiplexer in a single chip, or any other greater than 4-to-16?
 

The LS154 outputs are inverted because it is designed as an address decoder and the devices it would select normally have active low enable pins. I don't think there is a direct equivalent with active high outputs. You can always invert the polarity with a second IC or discrete devices.

When more decoded outputs are needed, the usual practise is to chain several decoders together, for example, one 74LS138 can select eight other LS138 ICs to give 64 outputs or you could use one LS154 to select 16 other LS154s to get 256 outputs. You culd always make your own from PLDs, it's easier than you thnk.

Brian.
 
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    neazoi

    neazoi

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betwixt said:
The LS154 outputs are inverted because it is designed as an address decoder and the devices it would select normally have active low enable pins. I don't think there is a direct equivalent with active high outputs. You can always invert the polarity with a second IC or discrete devices.
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Each of the multiplexer outputs will be used to drive a 74LS74 flip flop, to retain the output bit. Maybe I could avoid using inverter chips by finding a flip flop that has inverted outputs. Is there such one like the 74LS74 but with inverted inputs?

More flip flops in the same chip are desired too, if such a chip exists.

Thank you very much!
 

The 74LS74 already has inverted outputs! Just use the -Q instead of Q output pin.

It sounds like what you really need is an addressable latch rather than a decoder. Look at the data sheet for the 74HCT259, is this what you need? It can be expanded to more outputs by using it's enable pin.

Brian.
 

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